Amplifier



FIG. 1 is a perspective view of an amplifier, embodying my new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a left side elevation view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

Portions of the figures that are shown as broken lines are for illustrative purpose only and form no part of the claimed design. 

The ornamental design for an amplifier, as shown and described. 